Qiang Luo

It seems in py2 instance method cannot be pickled in default. https://gist.github.com/luoq/703ec045827caf5a504ff97376db9c3e https://stackoverflow.com/questions/1816958/cant-pickle-type-instancemethod-when-using-multiprocessing-pool-map?rq=1

It's fixed after python3.5: https://stackoverflow.com/questions/45901505/python3-6-can-pickle-instance-method-staticmethod-classmethod-but-document-say